Yellowstone National Park.☞文章内容an easy day hike or boat trip can turn into a battle for survival.

    Grown-ups are often surprised by how well they remember something they learned as children but have never practiced ever since. A man who has not had a chance to go swimming for years can still swim as well as ever when he gets back in the water. He can get on a bicycle after many years and still ride away. A mother who has not thought about the words for years can teach her daughter the poem that begins "Twinkle, twinkle, little star" or remember the story of Cinderella or Goldilocks and the Three Bears.

    One explanation is the law of overlearning, which can be stated as follows: Once we have learned something, extra learning attempts or tries to increase the length of time we will remember it.

    In childhood we usually continue to practice such skills as swimming, and bicycle riding long after we have learned them. We continue to listen to and remind ourselves of words such as "Twinkle, twinkle, little star" and childhood tales such as Cinderella and Goldilocks. We not only learn but overlearn.

    The multiplication tables(乘法口诀表) are an exception（例外） to the general rule that we forget rather quickly the things that we learn in school, because they are another of the things we overlearn in childhood.

    The law of overlearning explains why cramming(突击学习)for an examination, though it may result in a passing grade, is not a satisfactory way to learn a college course. By cramming, a student may learn the subject well enough to pass the examination, but he is likely soon to forget almost everything he learned. A little overlearning, on the other hand, is really necessary for one's future development.

    Billie Holiday was an American jazz singer and songwriter. Nicknamed Lady Day by her loyal friend and musical partner, Lester Young, Holiday had a great influence on jazz and pop singing. Her voiced style, strongly inspired by jazz instrumentalists, pioneered a new way of controlling tempo (节奏). Above all, she was admired for her deeply personal and direct approach to singing.

    She co-wrote a few songs, and several of them have become jazz standards, notably God Bless the Child, Don't Explain, and Lady Sings the Blues. She also became famous for singing jazz standards written by others, including Easy Living and Strange Fruit.

    Her early career is hard to track down with accuracy. But she later gained work singing in local jazz clubs before being spotted by a talent scout (星探), John Hammond in 1933.

    Her voice and recordings were loved for the depth of emotion and intensity she could bring to classic standards. Her range of voice was not the greatest, but her extraordinary low rough voice was soon to become very famous and influential.

    She was an important icon (偶像) of the jazz era and influential in the development of jazz singing. In the late 1930s, she began singing a civil rights song called Strange Fruit, a song which told the tale of a lynching (用私刑处死) of a black man in the Deep South. It was very controversial for that period and it was not played on radios. It was recorded for Commodore Records and she performed it many times over the next 20 years.

    Billie Holiday had a difficult upbringing which influenced her attitude toward life. She experienced many violent relationships. She also became increasingly dependent on various drugs which contributed to her early death in 1959, aged just 44.

    As the weather costs you a loss on trains and flights, we look at your rights.

Cancelled trains

    On a single ticket, a passenger will usually receive 25% of the fare if the train is delayed by 15 minutes. If the delay reaches 30 minutes, the compensation（补偿金）rises to 50%, and if it's over an hour you should be able to reclaim the whole cost. Clear arrangements vary according to train operators（运营商）.

    If you were due to travel, to say Aberdeen from London, your train is cancelled and you decide not to travel, you can get a full compensation. If you had a non-cancelable ticket with one operator, and failed to make that train because the connecting train was delayed, you can take the next available train.

Flights

    If your flight is cancelled because of the snow you have the right to s full compensation of the ticket, or to be rerouted home on a later flight.

    But you will have no right to get a delay or cancellation compensation under EU rules, because the snow is an extraordinary circumstance beyond the airline's control. If you don't take the compensation and choose to be rerouted, and it means you are stuck at the airport overnight, it's the airline's duty to pay for a reasonably priced hotel room and meals.

    The airline has to reroute you at the earliest opportunity, or at the passenger's free time, you are supposed to take the availability of seats.

    If you choose to be rerouted or if your departure is delayed by more than two hours, airlines also have to provide assistance such as food. The airlines keep this quiet and getting the money out of the low-cost operators can be a hard job. Keep evidence of cancellations, all receipts, and use your mobile to video any offer to pay by airline staff.

    The National Gallery

    Description:

    The National Gallery is the British national art museum built on the north side of Trafalgar in London. It houses a diverse collection of more than 2,300 examples of European art ranging from 13th-century religious paintings to more modern ones by Renoir and Van Gogh. The older collections of the gallery are reached through the main entrance while the more modern works in the East Wing are most easily reached from Trafalgar Square by a ground floor entrance.

    Layout:

    The modern Sainsbury Wing on the western side of the building houses 13th-to15th-century paintings, and artists include Duccio, Uccello, Van Eyck, Lippi, Mantegna, Botticelli and Memling.

    The main West Wing houses 16th-century paintings and artists include Leonardo da Vinci, Cranach, Michelangelo, Raphael, Bruegel, Bronzino, Titian and Veronese.

    The North Wing houses 17th-century paintings and artists include Caravaggio, Rubens, Poussin, Van Dyck, Velazquez, Claude and Vermeer.

    The East Wing houses 18th-to early 20th-century paintings, and artists include Canaletto, Goya, Turner, Constable, Renoir and Van Gogh.

    Opening Hours:

    The Gallery is open every day from 10am to 6pm（Fridays 10am to 9pm）and is free, but charges apply to some special exhibitions.

    Getting There:

    Nearest underground stations: Charing Cross (2-minute walk). Leicester Square (3-minute walk), Embankment (7-minute walk), and Piccadilly Circus (8-minute walk).

    Researchers have created a backpack that has a computer and medicines in it that can help even untrained soldiers save the lives of wounded troops. Wounded soldiers have a better chance of survival if they get help soon after being hurt and are quickly taken to a hospital or clinic. But soldiers who do not have medical training may not know how to help their injured friends.

    Doctors and engineers have developed what they call an “intelligent backpack”. It has a computer and electronic measuring devices. The backpack also has robotic instruments and medicines ready to give to injured troops.

    About 16 doctors and engineers from the University of Pittsburgh, Carnegie Mellon University and several other places are working on the project. The U. S. Department of Defense has given money to the project.

    Ron Poropatich leads the project. He is a retired army surgeon. He says the backpack will help soldiers care for those who are injured. The devices included in the backpack can monitor a person's heart rate and blood pressure. The robotic instruments can even tell whether the soldier has a collapsed lung.

    The intelligent backpack's computer can compare information gathered about the injured soldier with thousands of similar cases, and quickly tell the best methods to use to save the soldier's life.

    Sometimes, it is not always possible to quickly remove the injured soldier from the battlefield. So, Dr. Poropatich says, the researchers hope to create a backpack that will have devices that can keep a soldier alive for a long time. Dr. Poropatich hopes the backpack and its instruments will be ready for testing animals in about three years.

    A lifetime of active exercise will let you keep the body of a 20-year-old well into your 70s, scientists have found.

    The physical decline (衰退) thought to be an unavoidable part of ageing is actually the result of not exercising enough, according to the research, which found that regular cyclists kept the muscles, lungs, and even the immune system (免疫系统) of people years younger. Besides, many serious health problems could be prevented if people became more active, researchers insist.

    Janet Lord, a leading researcher, said, “Our findings prove the false belief that ageing automatically makes us weaker. We now have strong evidence that encouraging people to do regular exercise throughout their lives can solve the problem that we are living longer but not healthier.”

    She looked at 125 cyclists aged 55 to 79 who had been exercising regularly for 25 years and compared them with 75 ordinary people of a similar age and 55 people aged 20 to 36. On a series of physical measures, the cyclists showed no difference from people much younger in their immune systems and making T cells.

    Now Professor Lord aims to discover how much exercise people need to do to stay young. “You needn't work out a lot. It may be intensity (强度) that helps—like going up and down the stairs ten times a day.”

    While there is no magic method of staying mentally and physically fit in later life, the benefits of keeping active can never be ignored, whatever your age or state of health.